Autism Spectrum Disorders (ASD) is a grouping of developmental disorders that cause impairments in the functioning of children and can have devastating long-term effects on individuals and their families. Early diagnosis is a critical factor in ameliorating the affects of ASD on children's social and communicative functioning. The recent discovery of the relatively high prevalence of this disorder, 1 in 110 children, has accentuated the demand for diagnostic services and consequently the need for increased access to quality training on this topic for school professionals working with children. Innovations in multimedia computer technology and improvements in the ease of access to computer-based programs and videos via the Internet hold great promise for enhancing current clinical training methods and increasing access to current research- based information. DiagnoseFirst will help professionals learn to better identify the markers for ASD in children ages three to ten years. It will combine visuals of real world practicum experience with web based delivery for broad distribution. To improve the quality of diagnosis, a weighted measurement for agreement of behavior interpretation between experts will be expanded to permit a transparent understanding of complex behaviors used in diagnosis and provide a consensus for diagnostic interpretation between experts that does not exist presently. DiagnoseFirst offers a more efficient, lower cost, consistent methodology for training university students, professionals and clinicians to accurately diagnose ASD in school aged children. This program meets the NIH goal of improving diagnostic services for children with disorders.